The Marine Corps said in a statement that General Eric Smith, the service’s acting commandant, “directed all Marine Corps aviation units to conduct a two-day pause in operations this week to discuss aviation safety matters and best practices”. It cited three “Class A” mishaps in the last six weeks: the F-35 lost on Sunday as well as two other “Class A” incidents: the crashes of an F/A-18 in California that killed the pilot and an MV-22 Osprey in Australia that killed five Marines.

Earlier, the military asked for civilian help in finding the F-35B Lightning II jet that suffered a “mishap” on Sunday afternoon, according to social media posts by Joint Base Charleston, an air base in South Carolina.

The base said emergency response teams have been joined by Navy and civil air patrol teams trying to find the plane. “Teams continue to search for the US Marine Corps F-35B, using ground and air assets,” the base said in a post Monday afternoon.

The unidentified pilot ejected safely, was taken to a local hospital and is in stable condition, according to the Marine Corps, which operates the jet.

Transponder Questions

The military’s inability to track the sophisticated aircraft raised questions about whether its transponder, a device that sends out signals on a plane’s location, was working properly during the flight and after the pilot’s ejection.

“We’re not certain exactly what the issue with the transponder was, but the bottom line was that we needed the public’s help to track the plane,” said Jeremy Huggins, a civilian spokesperson at the base in Charleston. Transponders “should normally be working”, he said. “That’s a requirement we have.”

The air base said it was working with Marine Corps Air Station Beaufort to search for the plane north of North Charleston around Lake Moultrie and Lake Marion, based on its last-known location.

“The mishap is currently under investigation,” the 2nd Marine Aircraft Wing said in a statement. “The Department of the Navy has a well-defined process for investigating aircraft mishaps. We are unable to provide additional details to preserve the integrity of the investigatory process.”

Lockheed Martin is the manufacturer of the F-35, a single-seat fighter craft used by militaries around the world. The aircraft was a vertical take-off version used by in the Marine Corps. The jet is prized for its stealth qualities that make it difficult to detect by radar.

“We are aware of the mishap and are thankful the pilot ejected safely,” Lockheed said in a statement. “We are supporting the government’s investigation.”

The F-35 programme, the most expensive US weapons program ever, is projected to cost $412-billion in development and acquisition, plus an additional $1.2-trillion to operate and maintain the fleet over more than 60 years. A single jet can cost more than $160-million, depending on the variant. They are flown by the Air Force and Navy as well as the Marines.

It’s not the first time an F-35 has been in trouble. An F-35B version crashed in 2018 in Beaufort County, South Carolina, because of a manufacturing defect in a fuel tube, according to a Government Accounting Office’s report. The following year, a Japanese F-35A stealth fighter plunged into the ocean during an exercise over the Pacific Ocean, which Japan blamed on pilot disorientation, rather than technical issues.

Online Mockery

The missing aircraft in the US swiftly drew online mockery, from postings with Missing-Jet fliers on lamp posts and notices on milk cartons, to mashed-up Dude, Where’s My F-35 movie posters.

“How in the hell do you lose an F-35?” South Carolina Republican Representative Nancy Mace said on social media. “How is there not a tracking device and we’re asking the public to what, find a jet and turn it in?”